Based on the particularity of the fouling in the sewage heat exchanger, proposed a new heat exchanger with on-line hydraulic removing fouling technology, focused on the structure and principle of this heat exchanger, designed and manufactured the experimental prototype, and determined the best scheme based on analyzing the technical and economic feasibility of various irrigation programs. The experimental results shows that keeping each tube washed for one minute with 5m/s and flushing 10 to 20 heat exchange tubes once a time is the feasible program both in technology and economy. That will give a new way of thinking for the sewage heat exchanger using vigorously in the engineering.